Bicycle frames and handlebars are eye-catching and essential parts to bicycles. Generally, the bicycle frames and the handlebars are made up of metal tubes, which are straight, smooth and plain. In addition, equal thick and equal diametral tubes are selected for forming the bicycle frames and the handlebars, according to assembling needs. Therefore, for creating fancy and attractive appearances of the bicycles, the tubes of the bicycle frames and the handlebars are only given with colors, patterns, or some regular curves.
For improving variety and appearances of the bicycle frames and the handlebars, a conventional method for molding particular shapes into a bicycle tube is described as below. The method applies a molding device with projecting blocks to mold a tube and the molding device is placed within the tube. Then, the molding device is expanded outwardly within the tubes so the tube is molded into particular shapes by the projecting blocks of the molding device. However, the conventional method requires the molding device to be placed within the tube, also the molding device and the projecting blocks are designed to expand outwardly accordingly. Therefore, the conventional method only could apply to a tube, which is straight, equal diameter and round, such as a handlebar stem, a front fork, and a chain stay etc.
By applying to the conventional method, the molding shapes of the bicycle tube are limited and it is difficult to mold a three-dimensional, fine and delicate shape, such as shapes of trademark patterns; therefore, it would be desirable to provide a method that could mold a three-dimensional, unique and delicate shape to the bicycle tube, for creating a designed, fashion, and integrated appearance or structure to bicycles.